But the MTA isn't happy about the signs. Representative Kevin Ortiz told WNYC: "These signs have the potential to cause crowding conditions in certain platform areas and will create uneven loading in that some train cars will be overcrowded while others will be under-utilized."

We asked the folks behind the Efficient Passenger Project, who asked to remain anonymous since the signs are unsanctioned, for their response. The MTA's stance is "simpleminded" and ignores the upsides of the signs, they told us:

"We believe that the plaques demonstrate the optimal loading position, not the only. Our first priority is safety (as we said multiple times on our website) - that's why we encourage people to find a spot near the sign. Commuters should be given more credit - they know whether it's safe to board the train or if it's too crowded.

"We believe the Efficient Passenger Project empowers the average rider. They can choose to follow the guidelines or they can find a more spacious spot elsewhere. Not every passenger is going to be privy to the project, so we think the MTA's position over-inflates a small potential detraction. The benefits overwhelmingly outweigh the negatives."

They are willing to work with the MTA to make the signs permanent, they added. But for the moment, they're not quitting: